U.S. patent application number 13/475852 was filed with the patent office on 2012-12-20 for fitting assembly.
This patent application is currently assigned to OPTIMIZE TECHNOLOGIES, INC.. Invention is credited to Robert DeLine, Douglas W. Ford.
Application Number | 20120319400 13/475852 |
Document ID | / |
Family ID | 47353088 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120319400 |
Kind Code |
A1 |
Ford; Douglas W. ; et
al. |
December 20, 2012 |
FITTING ASSEMBLY
Abstract
A fitting assembly for use in a fluid transfer assembly includes
a fluid conduit having a first fitting with first and second ends
and a bore extending between the first and second ends for
receiving the fluid conduit. The first end of the first fitting is
configured to sealingly dispose a ferrule assembly within a second
fitting in an engaged position. The fitting assembly further
includes a third fitting having first and second ends and a bore
extending between the first and second ends for receiving the fluid
conduit. The first end of the third fitting is configured to
sealingly dispose a collet assembly within the first fitting in an
engaged position.
Inventors: |
Ford; Douglas W.;
(Wilsonville, OR) ; DeLine; Robert; (Corbett,
OR) |
Assignee: |
OPTIMIZE TECHNOLOGIES, INC.
Oregon City
OR
|
Family ID: |
47353088 |
Appl. No.: |
13/475852 |
Filed: |
May 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12476931 |
Jun 2, 2009 |
8201854 |
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13475852 |
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61058091 |
Jun 2, 2008 |
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Current U.S.
Class: |
285/354 ;
29/525.11 |
Current CPC
Class: |
G01N 30/6039 20130101;
F16L 19/10 20130101; F16L 19/065 20130101; F16L 19/12 20130101;
Y10T 29/49963 20150115 |
Class at
Publication: |
285/354 ;
29/525.11 |
International
Class: |
F16L 19/04 20060101
F16L019/04; B23P 11/00 20060101 B23P011/00 |
Claims
1. A fitting assembly for use in a fluid transfer assembly having a
fluid conduit, the fitting assembly comprising: (a) a first fitting
having first and second ends and a bore extending between the first
and second ends for receiving the fluid conduit, the first end
configured to sealingly dispose a ferrule assembly within a second
fitting in an engaged position; (b) a third fitting having first
and second ends and a bore extending between the first and second
ends for receiving the fluid conduit, the first end configured to
sealingly dispose a collet assembly within the first fitting in an
engaged position.
2. The fitting assembly of claim 1, wherein the first end of the
first fitting is configured to bias the ferrule assembly into
releasable locking engagement with the fluid conduit in the engaged
position.
3. The fitting assembly of claim 2, wherein the ferrule assembly
comprises: (a) a frusto-conical seal portion having a tapered end,
an enlarged end, and a first bore sized and configured to receive
the fluid conduit, the seal portion formed from a first material;
and (b) a frusto-conical collet portion having a tapered end and an
enlarged end, the enlarged end of the collet portion mated with the
enlarged end of the seal portion, the collet portion having a
second bore in substantial alignment with the first bore, the
collet portion including at least one axial finger extending along
the tapered end that is configured to be biased into locking
engagement with the fluid conduit, wherein the collet portion is
formed from a second material.
4. The fitting assembly of claim 1, wherein the ferrule assembly
comprises a ferrule having a bore for receiving the fluid conduit,
a tapered end, and an enlarged end, and wherein the ferrule is made
from a polymeric material.
5. The fitting assembly of claim 1, wherein the first end of the
third fitting is configured to bias the collet assembly into
releasable locking engagement with the fluid conduit in the engaged
position.
6. The fitting assembly of claim 4, wherein the collet assembly
comprises a collet having a bore for receiving the fluid conduit,
the collet having a tapered end, an enlarged end, and at least one
axial finger extending along the tapered end that is configured to
be biased into locking engagement with the fluid conduit, the
enlarged end engageable by the first end of the third fitting.
7. The fitting assembly of claim 4, wherein the collet is formed
from a material chosen from the group consisting of a Titanium
alloy, stainless steel, a polymer, or a combination thereof.
8. The fitting assembly of claim 1, wherein the third fitting is
moveable into a disengaged position to move the collet assembly out
of sealing engagement with the first fitting.
9. The fitting assembly of claim 8, further comprising a capture
assembly configured to retain the third fitting within a portion of
the first fitting in the disengaged position.
10. The fitting assembly of claim 1, wherein the fluid conduit is a
silica conduit.
11. A method for assembling a fitting assembly for use in a fluid
transfer assembly having a fluid conduit, the method comprising:
(a) disposing a fluid conduit within the bores of a first fitting,
a collet assembly, a third fitting, and a ferrule assembly; (b)
positioning the fluid conduit within a chamber of a second fitting;
(c) engaging a first end of the first fitting with a portion of the
second fitting to sealingly dispose the ferrule assembly within the
second fitting; and (d) engaging a first end of the third fitting
with a portion of the first fitting to sealingly dispose the collet
assembly within the first fitting.
12. The method of claim 11, wherein the first end of the first
fitting is configured to bias the ferrule assembly into releasable
locking engagement with the fluid conduit when the first end of the
first fitting engages a portion of the second fitting.
13. The method of claim 12, wherein the ferrule assembly comprises:
(a) a frusto-conical seal portion having a tapered end, an enlarged
end, and a first bore sized and configured to receive the fluid
conduit, the seal portion formed from a first material; and (b) a
frusto-conical collet portion having a tapered end and an enlarged
end, the enlarged end of the collet portion mated with the enlarged
end of the seal portion, the collet portion having a second bore in
substantial alignment with the first bore, the collet portion
including at least one axial finger extending along the tapered end
that is configured to be biased into locking engagement with the
fluid conduit, wherein the collet portion is formed from a second
material.
14. The method of claim 11, wherein the ferrule assembly comprises
a ferrule having a bore for receiving the fluid conduit, a tapered
end, and an enlarged end, and wherein the ferrule is made from a
polymeric material.
15. The method of claim 11, wherein the first end of the third
fitting is configured to bias the collet assembly into releasable
locking engagement with the fluid conduit when the first end of the
third fitting engages a portion of the first fitting.
16. The method of claim 15, wherein the collet assembly comprises a
collet having a bore for receiving the fluid conduit, the collet
having a tapered end, an enlarged end, and at least one axial
finger extending along the tapered end that is configured to be
biased into locking engagement with the fluid conduit, the enlarged
end engageable by the first end of the third fitting.
17. The method of claim 15, wherein the collet is formed from a
material chosen from the group consisting of a Titanium alloy,
stainless steel, a polymer, or a combination thereof.
18. The method of claim 11, further comprising disengaging the
third fitting from the first fitting to move the collet assembly
out of sealing engagement with the first fitting.
19. The method of claim 18, further comprising retaining the third
fitting within a portion of the first fitting in the disengaged
position.
20. The method of claim 1, wherein the fluid conduit is a silica
conduit.
Description
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/476,931, filed Jun. 2, 2009, which claims
the benefit of U.S. Provisional Patent Application No. 61/058,091,
filed Jun. 2, 2008, the disclosures of which are hereby
incorporated by reference herein.
BACKGROUND
[0002] Numerous types of equipment used for the analysis or
purification of chemical compounds utilize miniature fluid
conduits, such as metallic tubing, through which liquid samples
pass. An analytical technique, such as liquid chromatography, uses
a column (conduit) packed with a packing material in order to
analyze and identify chemical properties of certain fluids. For
example, an analyte may be introduced into one end of the column,
and a carrier fluid then run through the column. The length of time
that the analyte is retained within the column can enable analysis
and identification of the analyte. A popular form of liquid
chromatography is High Performance Liquid Chromatography (HPLC) in
which the sample is pumped through the column under an elevated
pressure, typically at 300 to 6,000 psi. Another, relatively newer
liquid chromatography form is Ultrahigh Pressure Liquid
Chromatography (UHPLC) in which system pressure extends upward to
1400 bar or 20,000 psi, and possibly 30,000 psi. Both HPLC and
UHPLC are examples of analytical instrumentation that utilize fluid
transfer at elevated pressures.
[0003] Liquid chromatography systems, such as HPLC or UHPLC
systems, typically include several components. For example, such a
system may include a pump; an injection valve or autosampler for
injecting the analyte; a precolumn filter to remove particulate
matter in the analyte solution that might clog the column; a packed
bed to retain irreversibly absorbed chemical material; the HPLC
column itself; and a detector that analyzes the carrier fluid as it
leaves the column. These various components may typically be
connected by a miniature fluid conduit, such as metallic or
polymeric tubing, usually having an internal diameter of 0.003 to
0.040 inch.
[0004] All of these various components and lengths of tubing are
typically interconnected by threaded fittings. Fittings for
connecting various components and lengths of tubing are disclosed
in prior patents and patent applications, for example, U.S. Pat.
Nos. 5,525,303; 5,730,943; 5,911,954; and 6,095,572; and U.S.
Patent Application Publication No. 2008/0237112, filed on Jan. 9,
2008, the disclosures of which are herein all incorporated by
reference.
[0005] A typical threaded fitting 18 well known in the art is shown
in FIG. 1. The threaded fitting 18 includes an internally threaded
portion 20 formed near its open end that is suitable for threadably
receiving a second fitting, tightening device, etc., having an
external threaded portion (not shown). The fitting 18 further
includes an internal passageway 24 that narrows in diameter at its
distal terminus to form a female, cone-shaped chamber 28 defining a
frusto-conical sealing surface 26. The cone-shaped chamber 28 is in
communication with a cylindrical chamber 32 sized to receive tubing
34 therein. The cylindrical chamber 32 defines a "tube stop" 30 at
its end that closely and fully receives the tip of the tubing
34.
[0006] Often, the tubing interfaces with the threaded fittings with
a ferrule or similar sealing device (see ferrule 36 in FIG. 1). The
ferrule includes a cone-shaped end that allows it to be compressed
within the female cone-shaped chamber of the fitting and thus form
a liquid-tight seal. As is well known in the art, the tubing must
be seated on the bottom of the cylindrical chamber when the ferrule
is received within the fitting in order to ensure good
chromatography. This becomes even more critical in UHPLC where the
negative effects are greater. If the tube is not bottomed out in
the cylindrical chamber, the resulting chromatogram exhibits band
broadening due to mixing of the sample with the mobile phase. The
extra volume between the end of the tube and the cylindrical
chamber bottom is known as "dead volume." It is preferred that all
fitting connections after the pump be made as "zero-dead-volume"
connections to keep band broadening to a minimum. Even in
connections before the pump it can be critical that there is
"zero-dead-volume"because the extra volume will change the exact
nature of mixing solvents, giving a different delay volume from
various fitting connections.
[0007] The ferrule also secures on the tubing to prevent the tubing
from ejecting from the fitting at specified pressures. For
instance, HPLC ferrules are typically rated for pressures up to
6,000 PSI, and UHPLC ferrules are typically rated for pressures up
to 20,000 PSI. In UHPLC systems, stainless steel tubing is often
used to accommodate the high pressures. The ferrules are also
typically made of stainless steel to properly seal against the
tubing and to prevent the tubing from ejecting at the high
pressures. When the ferrule is forced into the female cone-shaped
chamber of the fitting, the ferrule swages down onto the tubing to
prevent the tubing from ejecting from the fitting. However, with
the ferrule being made of stainless steel, the ferrule swages onto
the stainless steel tubing as a hard swage. As such, the position
of the stainless steel ferrule cannot be readjusted on the tube,
if, for instance, it is desired to use the tubing with a different
fitting or component. Thus, if the stainless steel ferrule/tubing
is reused in a fitting of a slightly different size, a "dead
volume" is likely created between the end of the tube and the
cylindrical chamber tube stop, or the ferrule cannot seat in the
female cone-shaped chamber of the fitting, thereby causing the
connection to leak.
[0008] In HPLC systems, a ferrule made of a softer material may be
used such that a hard swage does not result. For instance, a
ferrule made from Polyetheretherketone (PEEK) or another similar
material may be used to seal the tubing within the fitting. The
PEEK ferrule creates a soft swage on the tubing; and therefore, the
position of the PEEK ferrule can be adjusted for use within
different fittings. However, PEEK ferrules cannot withstand the
extreme pressures of UHPLC systems.
[0009] Thus, it is desired to have a ferrule that can be re-used in
various UHPLC fittings while maintaining a liquid-tight seal and
preventing the tubing from ejecting at high pressures.
[0010] In certain HPLC and UHPLC systems, it is sometimes desirable
to use an inert capillary tube that may include polymeric material
or fused silica. For instance, the tubing may be comprised of
polymeric-clad fused silica or fused silica with polymeric sleeves
at the ends of the tubing. To be used within UHPLC systems,
however, the tubing must be able to withstand extreme pressures in
excess of 5,000 psi, often approaching 20,000 psi and beyond. In
that regard, the UHPLC systems require fitting ferrule assemblies
to secure tubing in place while making and maintaining a leak-tight
seal.
[0011] As noted above, traditional stainless steel ferrules work on
stainless steel tubing in a single-use fashion by swaging or
crimping onto the tube to grip and hold the tube in place within
the fitting, while at the same time forming a seal at the
connection. If stainless steel ferrules (or similar ferrules) are
used with fused silica tubing, it is desirable to sleeve or clad
the fused silica tubing with an outer layer of polymer, such as
PEEK. The PEEK outer sleeve provides a cushion between the
stainless steel ferrule and the fused silica tube to prevent
fracturing of the fused silica.
[0012] A polymeric ferrule, such as a PEEK ferrule, creates a soft
swage on the tubing. Therefore, a PEEK ferrule or similar ferrule
does not fracture or deform the more delicate tubing, such as
polymeric-clad fused silica or fused silica with polymeric sleeves
at the ends of the tubing. Moreover, the tubing can be repositioned
with respect to the PEEK ferrule, and the position of the PEEK
ferrule can be adjusted for use within different fittings.
[0013] However, PEEK ferrules in use with these tubings cannot
withstand the extreme pressures of UHPLC systems. Higher pressures
are difficult to achieve with polymer ferrules due to the limited
gripping ability of the ferrules on the outer polymer layer of the
tubing. At high pressures, the capillary tube ejects, resulting in
a system failure. In addition, the polymeric ferrule may creep on
the tubing over time due to its limited gripping ability or due to
elevated temperatures, thereby necessitating retightening within
the fitting to reinstate the grip of the ferrule on the capillary
tube.
[0014] A wrench or similar tool may be used to tighten the fitting
assembly and further compress the ferrule within the fitting
assembly and onto the tubing, thereby increasing the pressure
capabilities of PEEK or similar ferrules. However, by using a
wrench to tighten the fitting, as opposed to tightening the fitting
by hand, the tubing is often forced too tightly into the fitting
port. For instance, referring to FIG. 1, tubing 34 would be driven
into the cylindrical chamber 32 and may abut up against the tube
stop 30. If a more delicate material is used for the tubing, such
as silica, the tubing may fracture due to the over tightening.
[0015] Thus, there is additionally a need for a fitting and/or
ferrule assembly that grips and seals onto various types of tubes
(such as stainless steel, polymer-clad fused silica,
polymer-sleeved fused silica, etc.) used in HPLC and UHPLC systems
without breaking or deforming the tube.
SUMMARY
[0016] A ferrule for use in a fluid transfer assembly having a
fluid conduit is provided. The ferrule includes a frusto-conical
seal portion having a tapered end and an enlarged end and a first
cylindrical bore sized and configured to slidably receive a fluid
conduit. The seal portion is formed from a first material suitable
to seal the fluid conduit within a first fitting without
substantially deforming the fluid conduit.
[0017] The ferrule further includes a frusto-conical collet portion
having a tapered end and an enlarged end, wherein the enlarged end
of the collet portion is mated with the enlarged end of the seal
portion. The collet portion has a second cylindrical bore in
substantial alignment with the first cylindrical bore and at least
one axial finger extending along the tapered end that is configured
to be biased into locking engagement with the fluid conduit. The
collet portion is formed from a second material that substantially
prevents deformation of the fluid conduit when the finger is biased
into locking engagement with the fluid conduit.
[0018] A fitting assembly for use in a fluid transfer assembly
includes a fluid conduit having a first fitting with first and
second ends and a bore extending between the first and second ends
for receiving the fluid conduit. The first end of the first fitting
is configured to sealingly dispose a ferrule assembly within a
second fitting in an engaged position. The fitting assembly further
includes a third fitting having first and second ends and a bore
extending between the first and second ends for receiving the fluid
conduit. The first end of the third fitting is configured to
sealingly dispose a collet assembly within the first fitting in an
engaged position.
[0019] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This summary is not intended to identify
key features of the claimed subject matter, nor is it intended to
be used as an aid in determining the scope of the claimed subject
matter.
DESCRIPTION OF THE DRAWINGS
[0020] The foregoing aspects and many of the attendant advantages
of the present disclosure will become more readily appreciated by
reference to the following detailed description, when taken in
conjunction with the accompanying drawings, wherein:
[0021] FIG. 1 is a partial cross-sectional view of a prior art
fitting assembly for use in fluid transfer assemblies;
[0022] FIG. 2 is an isometric view of a hybrid ferrule formed in
accordance with one embodiment of the present disclosure;
[0023] FIG. 3 is an exploded view of the hybrid ferrule of FIG.
2;
[0024] FIG. 4 is cross-sectional view of the hybrid ferrule of FIG.
2, taken substantially across line 4-4;
[0025] FIG. 5A is a partial cross-sectional view of a first
exemplary embodiment of a fitting assembly for use in fluid
transfer assemblies shown in a first position, wherein the hybrid
ferrule of FIG. 2 is received within the fitting assembly;
[0026] FIG. 5B is a partial cross-sectional view of the fitting
assembly of FIG. 5A shown in a second position;
[0027] FIG. 6 is an isometric view of a second exemplary embodiment
of a fitting assembly for use in fluid transfer assemblies, wherein
the hybrid ferrule of FIG. 2 is received within the fitting
assembly;
[0028] FIG. 7 is an exploded view of the fitting assembly of FIG.
6;
[0029] FIG. 8A is a cross-sectional view of the fitting assembly of
FIG. 6 shown in a first position;
[0030] FIG. 8B is a cross-sectional view of the fitting assembly of
FIG. 6 shown in a second position;
[0031] FIG. 8C is a cross-sectional view of the fitting assembly of
FIG. 6 shown in a third position; and
[0032] FIG. 9 is a cross-sectional view of a third exemplary
embodiment of a fitting assembly for use in fluid transfer
assemblies.
DETAILED DESCRIPTION
[0033] Referring to FIGS. 2-4, a hybrid ferrule 40 formed in
accordance with one embodiment of the present disclosure is
depicted. The hybrid ferrule 40 is suitable for use in fluid
transfer assemblies for scientific instruments such as HPLC and
UHPLC systems. For ease of description and illustration, the hybrid
ferrule 40 will be hereinafter described as being used in a portion
of a first exemplary embodiment of a UHPLC fitting assembly 44.
However, it should be appreciated that the hybrid ferrule 40 may
instead be used in any suitable system or assembly. Thus, the
description hereinafter provided should not be seen as limiting the
scope of the claimed subject matter.
[0034] Referring still to FIGS. 2-4, the hybrid ferrule 40 will now
be described in detail. The hybrid ferrule 40 includes a seal
portion 48 mated with a collet portion 52. The seal portion 48 is
formed from a material suitable for sealing within the UHPLC
fitting assembly 44, such as Polyetheretherketone (PEEK), and the
collet portion 52 is formed from a material suitable for gripping
onto the tubing of the fitting assembly 44, such as hardened
Titanium alloy. The design and materials of the hybrid ferrule 40
allow the ferrule 40 to seal within a threaded fitting and
withstand the extreme pressures of UHPLC, while at the same time
being adjustable and reusable within various fittings, as will
become apparent from the description below.
[0035] The seal portion 48 and collet portion 52 define first and
second interior axial bore portions 60 and 62, respectively. The
first and second interior axial bore portions 60 and 62 are
substantially identical in diameter and cross-sectional shape such
that when aligned, the first and second interior axial bore
portions 60 and 62 define a substantially smooth interior
cylindrical passageway 64 of constant diameter. In the alternative,
the first and second interior axial bore portions 60 and 62 may
instead define seal portion 48 and collet portion 52 interior
surfaces that are textured, grooved, threaded, etc., to aid in
gripping onto the exterior surface of the tubing 34. The interior
cylindrical passageway 64 is configured to slidably receive a
portion of a UHPLC fluid conduit therein. Preferably, the interior
cylindrical passageway 64 receives stainless steel tubing 34 of a
predetermined outer diameter having an internal fluid passageway
42. It should be appreciated that the first and second interior
axial bore portions 60 and 62 may be any suitable size to define an
interior cylindrical passageway 64 of a suitable diameter for
receiving tubing of a desired size, material, etc., for different
applications.
[0036] Both the seal portion 48 and the collet portion 52 are of a
generally frusto-conical or cone shape to define a double-ended
hybrid ferrule 40 when mated together. The seal portion 48 includes
a tapered end 54 and an enlarged end 58, wherein the enlarged end
58 defines a transverse end surface 66. An exterior, substantially
smooth tapered surface 56 extends from the enlarged end 58 to the
tapered end 54 such that the seal portion 48 is suitably sized and
shaped to be received within a portion of a threaded fitting. More
specifically, the seal portion 48 is configured to be tightly
received within the female, cone-shaped chamber 28 of the well
known threaded fitting 18 described above with respect to FIG. 1
(the same threaded fitting 18 is shown in FIGS. 5A and 5B and will
be described in further detail below).
[0037] Moreover, with the seal portion 48 being made from a
suitable material such as PEEK, the seal portion seals against the
fitting 18 and around the stainless steel tubing 34 to form a
liquid-tight seal without deforming the stainless steel tubing 20.
In this manner, the seal portion 48 forms a soft swage on the
tubing 20 so that the hybrid ferrule 40 can be repositioned on the
tubing 34 and reused in other fittings.
[0038] Preferably, the seal portion 48 defines a forty degree cone
such that it is suitably adapted to be received within a variety of
well-known threaded fittings similar to the fitting shown in FIGS.
1, 5A, and 5B. Such threaded fittings are readily available from a
variety of well known manufacturers, such as Optimize Technologies,
Inc., Swagelok Company, Parker Hannifin Corp, Valco Instruments
Company Inc., Rheodyne and Upchurch Scientific (both part of the
IDEX Health & Science Group), etc. For instance, the seal
portion 48 may receive a 1/16th inch outer diameter tubing and fit
within a standard 1/16th inch swaged fitting. It should be
appreciated that the seal portion 48 may instead be larger or
smaller in size to fit within various fittings for different
applications.
[0039] The seal portion 48 further includes an annular
collet-engaging protrusion 68 that extends axially from the end
surface 66 of the seal portion 48. The annular collet-engaging
protrusion 68 defines a substantially cylindrical outer surface 72
that extends from the tapered surface 56 of the of the seal portion
48. The cylindrical outer surface 72 includes a center longitudinal
axis that is substantially collinear with the cylindrical
passageway 64 of the hybrid ferrule 40. It should be appreciated
that the outer surface 72 of the annular collet-engaging protrusion
68 may instead be curved or any other suitable contour. The annular
collet-engaging protrusion 68 includes an inwardly extending lip 74
on its distal end that defines an annular receptacle or groove 76
between the lip 74 and the enlarged end surface 66 of the seal
portion 48. The groove 76 is sized and configured to receive a lip
78 of a correspondingly shaped protrusion 82 of the collet portion
52.
[0040] The protrusion 82 of the collet portion 52 extends axially
outwardly from a transverse end surface 92 of the collet portion 52
such that its center longitudinal axis is substantially collinear
with the cylindrical passageway 64 of the hybrid ferrule 40.
Moreover, the inner surface of the protrusion 82 extends from and
is in substantial alignment with the surface of the second interior
axial bore portion 62. In this manner, the interior surface of the
cylindrical passageway 64 remains substantially smooth and of
constant diameter such that the hybrid ferrule 40 may slidably
receive a portion of UHPLC tubing or other suitable tubing therein.
The lip 78 extends outwardly from the protrusion 82 to define an
annular receptacle or groove 84 between the lip 78 and the end
surface 92 of the collet portion 52. The groove 84 is sized and
shaped to receive the lip 78 of the protrusion 68 extending from
the seal portion 48.
[0041] As shown in FIG. 4, the collet portion 52 is secured to the
seal portion 48 by mating the protrusion 82 of the collet portion
52 with the protrusion 68 of the seal portion 48. More
specifically, the lip 78 of protrusion 82 is received within
annular groove 76, and the lip 74 of protrusion 68 is received
within annular groove 84. In this manner, the collet portion 52 and
seal portion 48 are "snap fit" together to define the hybrid
ferrule 40. With the collet portion 52 being made from Titanium and
the seal portion 48 being made from PEEK, the collet portion 52 and
seal portion 48 are preferably permanently secured together once
assembled. In any event, it is preferred that the seal portion 48
be sufficiently secured to the collet portion 52 such that the
hybrid ferrule 40 remains intact (the seal portion 48 remains
connected to the collet portion 52) when removing the hybrid
ferrule 40 from the fitting 18. Moreover, it should be appreciated
that the seal portion 48 may instead be molded or otherwise formed
on the collet portion 52 in any manner well known in the art.
[0042] As stated above, the collet portion 52 is of a generally
frusto-conical or cone shape. Similar to the seal portion 48, the
collet portion 52 includes a tapered end 86 and an enlarged end 88,
wherein the enlarged end 88 defines a transverse end surface 92. An
exterior, substantially smooth tapered surface 96 extends from the
enlarged end 88 to the tapered end 86 such that the collet portion
52 is suitably sized and shaped to be received within a portion of
a second fitting, or threaded nut 110. More specifically, and as
shown in FIGS. 5A and 5B, the collet portion 52 is configured to be
tightly received, or wedged within the female, cone-shaped chamber
126 of a well known externally torqued hexagonal nut 110. The nut
110 is threadably engageable with the threaded fitting 18 to
compress and secure the collet potion 52 onto the tubing 34.
Preferably, the collet portion 52 is configured to be received
within the female, cone-shaped chamber 126 of an OPTI-LOK EXP 10-32
Hex Head Male Nut, available from Optimize Technologies, Inc., of
Oregon City, Oreg. However, it should be appreciated that any other
suitable nut, fitting, tightening device, or clamping device may be
used to suitably compress the collet portion 52 onto the tubing
34.
[0043] The collet portion 52 further includes a plurality of axial
slots 100 extending from the tapered end 86 along at least a
portion of the collet portion 52 to define a plurality of axially
extending fingers 104. Preferably, the collet portion 52 includes
four axial slots 100 spaced equidistant from one another
circumferentially about the tapered end 86 of the collet portion 52
to define four substantially identical axially extending fingers
104. However, it should be appreciated that any suitable number of
axially extending fingers 104 may be used. In any event, it is
preferred that a suitable number of fingers be defined and the
fingers be of a suitable width and length such that they may be
deformed onto the tubing 34 when engaged by the nut 110 without
breaking off from the collet portion 52.
[0044] The fingers 104 deform or contract radially onto the tubing
34 when an external axial force is exerted on the fingers 104 by
the female, cone-shaped chamber 126 of the nut 110. In this manner,
the collet portion 52 is secured onto the tubing 34 to prevent the
tubing 34 from ejecting at extreme pressures. With the collet
portion 52 being made from a Titanium alloy or another suitable
material, the fingers 104 spring back into their original position
when the nut 110 is disengaged from the collet portion 52 such that
the tubing 34 may be readjusted or removed from the ferrule 40. In
addition, the collet portion 52 does not form a hard swage on the
stainless steel tubing 34.
[0045] Moreover, as stated above, the seal portion 48 is made from
PEEK or another suitable material such that it may seal within the
fitting 18 without forming a hard swage on the tubing 34. Thus, the
hardened Titanium collet portion 52 married to the softer PEEK seal
portion 48 provides a hybrid ferrule 40 that seals in the female,
cone-shaped chamber 28 of the fitting 18 while providing the grip
necessary to prevent the stainless steel tube 34 from ejecting at
high pressures. Moreover, the hybrid Titanium PEEK ferrule 40
secures onto the tubing without swaging irreversibly onto the
tubing 34.
[0046] Thus, the hybrid ferrule 40 provides the necessary grip to
withstand extreme pressures while providing the adjustability to be
used in fittings of different sizes and tolerances. The
adjustability feature is desirable, for example, when using either
different female 1/16th inch pieces from the same manufacturer or
when using 1/16 inch female fittings from different manufacturers.
In the first case, there are slight differences with respect to the
tube stop depth because of manufacturing tolerances, and the hybrid
ferrule 40 needs to be repositioned on the tubing 34 to enable the
tubing to bottom out in the cylindrical chamber 32 of the fitting
18. In the second instance, with different manufacturer's
dimensions, the tube stop depth may differ by as much as 0.040
inches. Without the use of the hybrid ferrule 40, the tubing would
either bottom out before the ferrule could engage the
frusto-conical sealing surface 26 of the cone-shaped chamber 28 to
make a seal, or the tubing would be off the bottom of the
cylindrical chamber 32 measurably. Thus, the adjustability of the
hybrid ferrule 40 enables the ferrule 40 to be reused in various
fittings.
[0047] Referring to FIGS. 5A and 5B, a description of the hybrid
ferrule 40 in use with a portion of the UHPLC fitting assembly 44
will be hereinafter described. The UHPLC fitting assembly 44
includes a fitting 18 as described above with respect to FIG. 1.
More specifically, the threaded fitting 18 includes an internally
threaded portion 20 formed near a first open end that is suitable
for threadably receiving the external threads of the nut 110. The
fitting 18 further includes a female, cone-shaped chamber formed at
its distal, internal end that defines a frusto-conical sealing
surface 26. The cone-shaped chamber is in communication with a
cylindrical chamber sized to receive the end of the tubing 34
therein.
[0048] The fitting 18 further includes a passage 38 that is in
communication with the cylindrical chamber and aligns with the
fluid passageway 42 of the tubing 34 when the tubing is received
within the cylindrical chamber. The fitting 18 may be threadably
connected to a connection device 140 at a second open end of the
fitting for placing the tubing 34 into communication with, for
instance, a column, trap, etc., received within a cylindrical
opening 144 in the connection device 140. It should be appreciated
that the connection device 140 may be any suitable device used in
UHPLC systems or other suitable systems.
[0049] To assemble the fitting assembly 44, the tubing 34 is
inserted within the cylindrical bores of the nut 110 and the hybrid
ferrule 40, and the tubing 34 is thereafter inserted into the
fitting 18. The tubing 34 is moved into the fitting 18 until the
tubing 34 is received within the cylindrical chamber of the female
port such that the tubing is substantially bottomed out against the
tube stop 30. Thereafter, the nut 110 may be tightened within the
fitting to secure the hybrid ferrule 40 in its position on the
tubing 34 and to define a liquid-tight seal between the tubing 34
and the fitting 18.
[0050] As described briefly above, the nut 110 is a well known
externally torqued hexagonal nut that is threadably engageable with
the threaded fitting 18 to compress and secure the collet potion 52
of the hybrid ferrule 40 onto the tubing 34. The nut 110 includes
an enlarged end 114 that may be hex-shaped or any other suitable
contour such that the nut 110 may be easily tightened within the
fitting either by hand or with a suitable tool. The nut includes a
threaded portion 118 extending from the enlarged end 114 and a
cylindrical bore 122 extending axially along the center of the nut
110. The cylindrical bore 122 widens at the threaded end of the nut
to define a frusto-conical chamber 126 having a collet-engaging
surface 130.
[0051] The frusto-conical chamber 126 is sized and shaped to engage
the collet portion 52 of the hybrid ferrule 40 and exert an axial
force on the collet portion 52 as the nut 110 is tightened into the
fitting 18. As shown in FIG. 5A, the collet-engaging surface 130
engages the fingers 104 of the collet portion 52 to compress the
fingers 104 onto the tubing 34 as the nut 110 is tightened. At the
same time, the collet portion 52 imparts an axial force against the
seal portion 56 to drive the seal portion into sealing engagement
with the frusto-conical sealing surface 26 of the fitting 18. More
specifically, referring back to FIG. 4, the protrusion 82 of the
collet portion 52 engages and imparts an axial force on the end
surface 66 of the seal portion 48 to drive the seal portion 48 into
sealing engagement against the frusto-conical sealing surface 26 of
the fitting 18. As such, the seal portion 48 is sealingly engaged
with the fitting 18 while the collet portion 52 is secured on the
tubing 34.
[0052] When it is desired to remove the tubing 34 from the fitting
18, the nut 110 is loosened until the collet-engaging surface 130
of the nut 110 no longer substantially engages the fingers 104 of
the collet portion 52. When this occurs, the fingers 104 spring
back into their original state such that the tubing 34 may slide
out from within the hybrid ferrule 40. Moreover, when the nut 110
and tubing 34 are removed from the fitting 18, the hybrid ferrule
40 may be removed from the fitting 18 for use in a different
application or fitting. If the seal portion 56 is "stuck" within
the cone-shaped portion of the fitting 18, the seal portion 48 may
be pulled out of sealing engagement with the fitting 18 by pulling
on the collet portion 52.
[0053] Referring to FIG. 5B, when the nut 110 is over-tightened
within the fitting 18, the protrusion 82 of the collet portion 52
imparts an axial force on the end surface 66 of the seal portion 48
to further compress the seal portion 48. Because the seal portion
48 is made from PEEK or another suitable material, the over
tightening causes a section of the seal portion 48 external of the
cone-shaped portion of the fitting 18 to bulge outwardly into the
space defined by the threaded and non-threaded portions 20 and 22
of the fitting 18. Such over tightening does not adversely affect
the sealing properties of the sealing portion 48. Moreover, when it
is desired to remove the tubing 34 from the fitting, the hybrid
ferrule 40 can be removed from the fitting in one piece and can be
re-used in its deformed state in another fitting. Thus, even when
the nut 110 is fully tightened within the fitting 18, the hybrid
ferrule properly seals within the fitting and secures on the tubing
34 to function in UHPLC systems.
[0054] Thus, it can be seen from the foregoing that the hybrid
ferrule 40 constructed of a PEEK seal portion 48 secured to a
Titanium collet portion 52 provides a ferrule that remains secured
on tubing when used in extreme pressure systems while maintaining a
liquid-tight seal within the fittings, wherein the ferrule may be
re-used or adjusted within the fitting to accommodate various
applications, fitting sizes, etc.
[0055] A second exemplary embodiment of a UHPLC fitting assembly
200 suitable for use with the hybrid ferrule 40 may best be seen by
referring to FIGS. 6 and 7. Generally described, the UHPLC fitting
assembly 200 is configured to suitably grip onto various types of
HPLC and UHPLC fluid conduits or tubing and seal the tubing within
the fitting assembly 200 without damaging or deforming the tubing.
For instance, the UHPLC fitting assembly 200 is suitable for
gripping and sealing onto polymer-clad fused silica tubing (e.g.,
PEEKsil.TM. tubing available from SGE Analytical Science of Austin,
Tex.), polymer-sleeved fused silica tubing, or other types of
tubing made from silica, borosilicate, glass silicates, etc.,
(hereinafter collectively referred to as "silica tubing" or a
"silica conduit"), stainless steel tubing, or other suitable types
of tubing used in HPLC and UHPLC systems without breaking or
deforming the tube.
[0056] It should be appreciated that any suitable tubing may be
used with the UHPLC fitting assembly 200. Moreover, although the
UHPLC fitting assembly 200 will be described as being tightened by
hand, in some embodiments the UHPLC fitting assembly 200 may be
configured to be tightened with a tool, such as a wrench. It should
further be appreciated that while the UHPLC fitting assembly 200 is
described for use with the collet 216 and the hybrid ferrule 40,
the fitting assembly 200 may instead be used with other suitable
collets and ferrule assemblies. Moreover, although the fitting
assembly 200 is described as a UHPLC assembly, suitable for use in
fluid transfer assemblies at 30,000 PSI or higher, the fitting
assembly 200 may also be adapted for use for HPLC assemblies. Thus,
the descriptions and illustrations provided herein should not be
seen as limiting the scope of the claimed subject matter.
[0057] Referring to FIGS. 6, 7, and 8A, the UHPLC fitting assembly
200 will now be described in detail. The UHPLC fitting assembly 200
includes a first fitting, or a threaded housing 204 that is
engageable with a second fitting, or a threaded fitting 208 (see
FIG. 8A), wherein a ferrule assembly, such as the hybrid ferrule 40
is sealingly disposed between the threaded housing 204 and the
threaded fitting 208. A third fitting, or a captured lock nut 212
is received within the threaded housing 204 opposite the threaded
fitting 208, with a collet assembly, such as a collet 216 sealingly
disposed between the lock nut 212 and the threaded housing 204.
[0058] Referring specifically to FIG. 8A, the threaded fitting 208
includes an internally threaded portion 224 formed near a first
open end that is suitable for engaging external threads of the
threaded housing 204. The threaded fitting 208 further includes a
female, cone-shaped chamber 226 formed at its distal, internal end
that defines a frusto-conical sealing surface 228. The cone-shaped
chamber 226 is in communication with a cylindrical chamber 230
sized to receive the end of the tubing 220 therein. The threaded
fitting 208 further includes a passage 232 that is in communication
with the cylindrical chamber 230 and aligns with the fluid
passageway of the tubing 220 when the tubing 220 is received within
the cylindrical chamber 230. The threaded fitting 208 may be
configured to place the tubing 220 into communication with, for
instance, a column, trap, etc., at a second end of the threaded
fitting (or through a suitable connection device).
[0059] Referring additionally to FIGS. 6 and 7, the threaded
housing 204 is engageable with the threaded fitting 208 to secure
the hybrid ferrule 40 therebetween in an "engaged" position. The
threaded housing 204 includes an enlarged end 234 at a first end
that is cylindrical in shape and includes a roughened or knurled
outer surface (not depicted). In this manner, the enlarged end 234
may be used to easily tighten the threaded housing 204 by hand or
with a suitable tool. It should be appreciated that the enlarged
end 234 may instead be another suitable overall shape, such as
hex-shaped, for tightening the threaded housing 204 by hand or with
a suitable tool.
[0060] The threaded housing 204 includes an externally threaded
portion 236 extending from the enlarged end 234 to define a second
end of the threaded housing 204, and an axial bore 238 extending
between the first and second ends. The externally threaded portion
236 is configured to be threaded into the internally threaded
portion 224 of the threaded fitting 208 into the "engaged"
position.
[0061] The axial bore 238 extends through the threaded housing 204
and widens at the second end to define a female, first
frusto-conical chamber 242 having a collet-engaging surface 246.
The first frusto-conical chamber 242 is sized and shaped to engage
the collet portion 52 of the hybrid ferrule 40 and exert an axial
force on the collet portion 52 as the threaded housing 204 is
tightened within the threaded fitting 208 in the engaged position.
By exerting an axial force on the collet portion 52, the threaded
housing 204 compresses the fingers of the collet portion 52 (not
labeled in FIGS. 6, 7, and 8A-8C) and secures the collet portion 52
of the hybrid ferrule 40 into releasable locking engagement on the
tubing 220. At the same time, the collet portion 52 imparts an
axial force against the seal portion 48 to drive the seal portion
48 into sealing engagement with the frusto-conical sealing surface
228 of the threaded fitting 208. As such, the seal portion 48 is
sealingly engaged with the threaded housing 204 while the collet
portion 52 is releasably secured on the tubing 220.
[0062] The threaded housing 204 is configured to exert an axial
force on the hybrid ferrule 40 when it is threaded into the
threaded fitting 208 in the engaged position. Similarly, the lock
nut 212 is configured to impart an axial force on the collet 216
when it is threaded into the threaded housing 204 in an "engaged"
position. In that regard, the threaded housing 204 includes a
second frusto-conical chamber 254 disposed opposite the first
frusto-conical chamber 242 that opens toward the first end of the
threaded housing 204. The second frusto-conical chamber 254 is
configured to sealingly receive the collet 216 therein. An axial
cylindrical chamber 250 extends between the first and second
frusto-conical chambers 242 and 254 to receive the tubing 220
therein.
[0063] The second frusto-conical chamber 254 transitions into a
first enlarged cylindrical axial bore portion 262, which
transitions into a threaded axial bore portion 266 of larger
interior diameter than the first enlarged cylindrical axial bore
portion 262. The threaded axial bore portion 266 defines a first
open end of the threaded housing 204 at the enlarged end 234 of the
threaded housing 204.
[0064] The threaded housing 204 is configured to receive a portion
of the lock nut 212 within its first open end so that the lock nut
212 may impart an axial force on the collet 216. In that regard,
the lock nut 212 includes an enlarged end 284 at a first end that
is cylindrical in shape and includes a roughened or knurled outer
surface (not depicted). In this manner, the enlarged end 284 may be
used to easily tighten the lock nut 212 by hand or with a suitable
tool. It should be appreciated that the enlarged end 284 may
instead be another suitable overall shape, such as hex-shaped, for
tightening the lock nut 212 by hand or with a suitable tool.
[0065] The lock nut 212 further includes an externally threaded
portion 282 defined near the second end of the lock nut 212, and a
reduced diameter portion 286 extending between the externally
threaded portion 282 and the enlarged end 284. An axial bore 288
extends within the interior of the lock nut 212 between the first
and second open ends for receiving the tubing 220. The externally
threaded portion 282 of the lock nut 212 is configured to be
threaded into the internally threaded axial bore portion 266 of the
threaded housing 204 to move the lock nut 212 into the engaged
position.
[0066] A cylindrically-shaped collet-engaging portion 280 extends
from the externally threaded portion 282 to define the second end
of the lock nut 212. The collet-engaging portion 280 is sized and
configured to be received within the first enlarged cylindrical
bore portion 262 of the threaded housing 204 such that the
collet-engaging portion 280 may engage the collet 216. More
specifically, a transverse end surface (not labeled) defined on the
collet-engaging portion 280 engages a transverse end surface 271
defined on the collet 216.
[0067] The collet 216 is substantially similar to the collet
portion 52 of the hybrid ferrule 40. The collet 216 is made from a
Titanium alloy or another suitable material and is generally of a
frusto-conical or cone shape. The collet 216 includes an annular
nut-engaging portion 270 at one end and a tapered portion 272
extending therefrom, with an axial bore 278 extending between the
opposite ends. The annular nut-engaging portion 270 defines a
transverse end surface 271 that is engageable by the
collet-engaging portion 280 of the lock nut 212.
[0068] The tapered portion 272 of the collet 216 is suitably sized
and shaped to be sealingly received within the second
frusto-conical chamber 254 of the threaded housing 204. More
specifically, and as shown in FIG. 8C, the tapered portion 272 is
configured to be tightly received, or wedged within the female,
second frusto-conical chamber 254 of the threaded housing 204. The
lock nut 212 engages the annular nut-engaging portion 270 to impart
an axial force on the collet 216 to drive the tapered portion 272
into the second frusto-conical chamber 254, thereby sealing the
collet 216 within the frusto-conical chamber 254.
[0069] At the same time, the collet 216 is compressed into
releasably locking engagement on the tubing 220 to suitably grip
onto the tubing 220. In that regard, the tapered portion 272
further includes a plurality of axial slots 274 extending along the
tapered portion 272 that define a plurality of axially extending
fingers 276. The axially extending fingers 276 are of a suitable
size, shape, and number such that the fingers may deform onto the
tubing 220 when engaged by the lock nut 212 without breaking off
from the collet 216.
[0070] The fingers 276 deform or contract radially onto the tubing
220 when an external force is exerted on the fingers 276 by the
female, second frusto-conical chamber 254 of the threaded housing
204. In this manner, the collet 216 is releasably secured onto the
tubing 220 to prevent the tubing 220 from ejecting at extreme
pressures. With the collet portion 220 being made from a Titanium
alloy or another suitable material, the fingers 276 spring back
into their original position when the lock nut 212 is disengaged
from the collet 216 such that the tubing 220 may be readjusted or
removed from the collet 216. In addition, the collet 216 does not
form a hard swage on the tubing 220. The interior surface of the
collet 216 extending along the axial bore 278 may further include
texture, grooves, threading, etc., to aid in gripping onto the
surface of the tubing 220.
[0071] It should be appreciated that although the collet 216 is
described as being made from a Titanium alloy or another suitable
material such that its fingers 276 may deform, the collet 216 may
instead be made from stainless steel, glass, a polymeric material,
such as PEEK, Nylon, or any other suitable materials. For instance,
if the collet 216 was made from PEEK, it would form a soft swage
onto the tubing 220, which would prevent damage to the tubing 220
when gripping onto the tubing 220. Moreover, the collet 216 may be
made from a combination of materials, such as glass or a suitable
metal (such as Titanium alloy) molded within a polymeric material.
For example, metal pieces may be molded within a polymeric material
so that the metal protrudes partially into the axial bore of the
collet. In this manner, the metal would aid in gripping onto the
tubing, while the polymeric material would form a soft swage on the
tubing. Furthermore, a plurality of collets formed from glass,
metal, etc. may be molded within a housing formed from a polymeric
material or another suitable material to further distribute the
gripping load along the tubing. Thus, it should be appreciated that
the collet 216 described and illustrated herein is exemplary only,
and the claimed subject should not be seen as limited in scope.
[0072] The annular nut-engaging portion 270 of the collet 216 may
have substantially the same outer diameter as the inner diameter of
the first enlarged cylindrical axial bore portion 262 of the
threaded housing 204. In this manner, as the collet 216 is moved
toward the second frusto-conical chamber 254, the tapered portion
272 of the collet 216 is aligned axially on the tubing 220. With
the collet 216 in axial alignment with the tubing 220, the collet
216 may suitably grip onto the tubing 220 and seal against the
collet-engaging surface 258 of the second frusto-conical chamber
254.
[0073] Likewise, the collet-engaging portion 280 of the lock nut
212 may have substantially the same outer diameter as the inner
diameter of the first enlarged cylindrical axial bore portion 262.
In this manner, the collet-engaging portion 280 may extend within
the first enlarged cylindrical axial bore portion 262 when driving
the collet 216 axially within the second frusto-conical chamber
254. Moreover, the transverse end surface of the collet-engaging
portion 280 may be sized to engage substantially the entire
transverse end surface 271 of the collet 216, thereby applying a
substantially uniform, distributed force to the collet 216.
[0074] As noted above, the lock nut 212 is movable into an engaged
position by engaging the externally threaded portion 282 of the
lock nut 212 with the internally threaded axial bore portion 266 of
the threaded housing 204. The fitting assembly 200 may also include
a lock nut capture assembly 290 configured to retain the lock nut
212 within the interior of the threaded housing 204, when the
externally threaded portion 282 of the lock nut 212 is disengaged
from the internally threaded axial bore portion 266 of the threaded
housing 204, or in a "disengaged" position.
[0075] The lock nut capture assembly 290 is defined by a second
enlarged cylindrical axial bore portion 292 formed within the first
end of the threaded housing 204. The inner diameter of the second
enlarged cylindrical axial bore portion 292 is larger than the
outer diameter of the reduced diameter portion 286 of the lock nut
212. In this manner, the lock nut 212 may be moved axially within
the interior of the threaded housing 204 into the engaged
position.
[0076] The lock nut 212 includes an annular protrusion 294 formed
on the outer surface of the reduced diameter portion 286. The
annular protrusion 294 is configured to engage an annular retaining
clip 296 received within an annular receptacle 298 defined within
the interior surface of the second enlarged cylindrical bore
portion 292. In this regard, when the externally threaded portion
282 of the lock nut 212 is disengaged from the internally threaded
axial bore portion 266 of the threaded housing 204 (i.e., in a
disengaged position), the annular retaining clip 296 will retain or
capture the lock nut 212 within the threaded housing 204.
[0077] It should be appreciated that any other suitable lock nut
capture assembly 290 may instead be used to capture the lock nut
212 within the threaded housing 204. Moreover, it should be
appreciated that in some embodiments, the lock nut capture assembly
290 may not be used such that the lock nut 212 is removable from
the threaded housing 204 in the disengaged position.
[0078] Referring to FIGS. 8A-8C, the operation of the fitting
assembly 200 will now be described in detail. Referring first to
FIG. 8A, the fitting assembly 200 is shown with threaded housing
204 disengaged from the threaded fitting 208, and with the lock nut
212 disengaged from the threaded housing 204. Tubing 220 extends
through the longitudinal axial bore of the fitting assembly 200
(defined by the axial bores of the lock nut 212, the collet 216,
the threaded housing 204, and the hybrid ferrule 40) and protrudes
from the hybrid ferrule 40. The tubing 220 is moved into the
threaded fitting 208 until the tubing 220 is substantially bottomed
out within the cylindrical chamber 230, as shown in FIG. 8A.
[0079] Referring to FIG. 8B, with the collet portion 52 of the
hybrid ferrule 40 positioned within the first frusto-conical
chamber 242 of the threaded housing 204, the threaded housing 204
is tightened within the threaded fitting 208 to move the threaded
housing 204 into the engaged position. Tightening the threaded
housing 204 within the threaded fitting 208 secures the hybrid
ferrule 40 in its position on the tubing 220 and defines a
liquid-tight seal between the tubing 220 and the threaded fitting
208.
[0080] More specifically, by tightening the threaded housing 204
within the threaded fitting 208 (i.e., in the engaged position),
the threaded housing 204 imposes an axial force on the collet
portion 52 of the hybrid ferrule 40 through the collet-engaging
surface 246. The collet portion 52 drives the PEEK seal portion 48
into sealing engagement with the frusto-conical sealing surface 228
of the threaded fitting 208. At the same time, the collet-engaging
surface 246 compresses the fingers of the collet portion 52 onto
the tubing 220 to securely position the hybrid ferrule 40 on the
tubing 220.
[0081] The threaded housing 204 may be hand-tightened within the
threaded fitting 208 rather than using a tool, such as a wrench. If
a tool was use to over-tighten the threaded housing 204 within the
threaded fitting 208, the PEEK seal portion 48 of the hybrid
ferrule 40 can deform, as described above with respect to FIG. 5B.
Deformation of the seal portion 48 can cause the tubing 220 to be
driven further into the cylindrical chamber 230, which can cause
the tubing to fracture. Thus, when the tubing is made of more
delicate materials (such as silica), hand tightening is preferred.
However, it should be appreciated that a tool may be used to
tighten the threaded housing 204 within the threaded fitting 208
with the same amount of force used for hand-tightening.
[0082] With the threaded housing 204 hand-tightened within the
threaded fitting 208 in the engaged position to secure the hybrid
ferrule 40 onto the tubing 220, the hybrid ferrule 40 can withstand
fluid pressures of up to about 15,000 psi. To increase the fluid
pressure capabilities of the fitting assembly 200, the lock nut 212
is moved into the engaged position, or it is tightened within the
threaded housing 204 to secure the collet 216 onto the tubing 220
and to seal the collet 216 within the threaded housing 204.
[0083] Referring to FIG. 8C, the lock nut 212 is tightened within
the threaded housing 204 by gripping and turning the enlarged
portion 284 of the lock nut 212. In certain embodiments, the
threading is configured such that only about one quarter (1/4) of a
turn is needed to fully tighten the lock nut 212 within the
threaded housing 204 (i.e., moved into the engaged position).
[0084] When moved into the engaged position, the collet-engaging
portion 280 of the lock nut 212 imparts an axial force onto the
annular nut-engaging portion 270 of the collet 216. The collet 216
is driven into engagement with the collet-engaging surface 258 of
the second frusto-conical chamber 254 to seal the collet 216 within
the second frusto-conical chamber 254. At the same time, the
collet-engaging surface 258 compresses the fingers 276 of the
collet 216 onto the tubing 220 to securely position the collet 216
on the tubing 220.
[0085] When the collet 216 is compressed onto the tubing 220, the
collet 216 grips onto the tubing 220 without driving the tubing 220
further towards the hybrid ferrule 40 (and therefore, further
within the cylindrical chamber 230). Moreover, as noted above, with
the threaded housing 204 tightened within the threaded fitting 208
in the engaged position, the tubing 220 is securely positioned
within the hybrid ferrule 40. As such, the tubing 220 is not driven
further into the cylindrical chamber 230, preventing any fracturing
of the end of the tubing 220.
[0086] In that regard, the threaded housing 204 may be either
hand-tightened within the threaded fitting 208 or may instead be
tightened with a tool. Hand-tightening the threaded housing 204
within the threaded fitting 208 will sufficiently compress the
collet 216 onto the tubing 220. However, because there is no danger
of driving the tubing 220 further into the cylindrical chamber 230
(with the possibility of fracturing the tubing 220), a tool may
instead be used.
[0087] The gripping force of the collet 216 in addition to the
hybrid ferrule 40 enables the fitting assembly 200 to withstand
fluid pressures up to about 30,000 psi and higher. Moreover, the
gripping load is distributed over two areas of the tubing 220,
rather than point loading at only a single ferrule assembly, which
can cause damage to the tubing. It should be appreciated that the
fitting assembly 200 may be modified to include additional collet
and ferrule assemblies for gripping onto the tubing 220. In this
manner, the gripping load may be distributed over three or more
areas of the tubing 220. By distributing the load over three of
more areas of the tubing, the fitting assembly 200 may be able to
withstand fluid pressures much greater than 30,000 psi. Thus, it
should be appreciated that the fitting assembly 200 may be adapted
or modified to include less or more areas of distributed load for
the intended application.
[0088] To remove or otherwise reposition the tubing 220 within the
fitting assembly 200, the lock nut 212 is loosened by hand (or with
a tool, depending on how originally tightened) to loosen the grip
of the collet 216 on the tubing 220 and move the lock nut 212 into
the disengaged position. With the lock nut 212 in the disengaged
position, the fingers 276 of the collet 216 may spring back to
their original, undeformed state (see FIG. 8B).
[0089] Similarly, the threaded housing 204 is loosened by hand to
loosen the grip of the hybrid ferrule 40 on the tube 220 and move
the threaded housing 204 into the disengaged position. The threaded
housing 204 may be removed from within the threaded fitting 208,
thereby allowing the fingers of the collet portion 52 of the hybrid
ferrule 40 to spring back to their original, undeformed state (see
FIG. 8A). With the collet 216 and hybrid ferrule 40 loosely
disposed on the tubing 220, the position of the fitting 200 may be
readjusted on the tubing 220, or a new fitting may be used with the
same tubing 220.
[0090] Referring to FIG. 9, a third exemplary embodiment of a UHPLC
fitting assembly 300 will now be described. The fitting assembly
300 is configured to suitably grip onto various types of HPLC and
UHPLC tubing and seal the tubing within the fitting assembly 300
without damaging or deforming the tubing. For instance, the UHPLC
fitting assembly 300 is suitable for gripping and sealing onto
stainless steel tubing, silica tubing, or other suitable types of
tubing used in HPLC and UHPLC systems without breaking or deforming
the tubing.
[0091] The fitting assembly 300 is substantially similar to the
fitting assembly 200 described above except for the differences
hereinafter provided. In that regard, reference numerals used to
describe and illustrate components of the fitting assembly 200 have
been used for description and illustration of the fitting assembly
300 where the components are substantially identical.
[0092] The fitting assembly 300 differs from fitting assembly 200
described above in that the hybrid ferrule 40 is not disposed
within the threaded fitting 208. Rather, a ferrule 320 is received
within the threaded fitting 208 for engaging and sealing against
the frusto-conical sealing surface 228 of the cone-shaped chamber
226. The ferrule 320 includes an annular fitting-engaging portion
324 at a first end of the ferrule 320 that defines a transverse end
surface (not labeled). The transverse end surface of the
fitting-engaging portion 324 is engageable by a portion of the
threaded housing 304 to drive the ferrule 320 into the threaded
fitting 208 when the threaded housing 304 is in an engaged
position. A tapered portion 328 extends from the fitting-engaging
portion 324 that is engageable with the frusto-conical sealing
surface 228. The ferrule 320 may be comprised of a polymeric
material, such as PEEK, to seal against the frusto-conical sealing
surface 228. Moreover, the polymeric ferrule 320 forms a soft swage
as it grips onto the tubing 220, thereby preventing any damage to
the tubing 220.
[0093] The threaded housing 304 is substantially similar to
threaded housing 204 described above. In that regard, the threaded
housing 304 is configured to receive a collet 316 in a second
frusto-conical chamber 354, wherein the collet 316 is substantially
similar to collet 216 described above. In that regard, when the
collet 316 is driven into the second frusto-conical chamber 354 and
compressed onto the tubing 220, the collet 316 grips onto the
tubing 220 without driving the tubing 220 further towards the
ferrule 320 (and therefore, further within the cylindrical chamber
230). As such, the tubing 220 is not driven further into the
cylindrical chamber 230, preventing any fracturing of the end of
the tubing 220.
[0094] However, the threaded housing 304 does not include a first
frusto-conical chamber at its second end. Rather, the second end is
defined by a ferrule-engaging portion 332 that is configured to
engage and impart an axial force on the ferrule 320. The
ferrule-engaging portion 332 defines a transverse end surface (not
labeled) that is engageable with the transverse end surface of the
fitting-engaging portion 324 of the ferrule 320.
[0095] The gripping force of the collet 316 in addition to the
ferrule 320 enables the fitting assembly 200 to withstand higher
fluid pressures than if the ferrule 320 was used alone. Moreover,
the gripping load is distributed over two areas of the tubing 220,
rather than point loading at only a single ferrule assembly, which
can cause damage to the tubing 220.
[0096] To remove or otherwise reposition the tubing 220 within the
fitting assembly 300, the lock nut 212 is loosened by hand (or with
a tool, depending on how originally tightened) to loosen the grip
of the collet 316 on the tubing 220. The lock nut 212 is loosened
until it moves into the disengaged position, thereby allowing the
fingers of the collet 316 to spring back to their original,
undeformed state.
[0097] Similarly, the threaded housing 304 is loosened by hand to
loosen the grip of the ferrule 320 on the tubing 220. The threaded
housing 304 may be removed from within the threaded fitting 208,
thereby allowing the polymeric ferrule 320 to be removed from
within the threaded fitting 208 and the tubing 220. With the collet
316 and ferrule 320 loosely disposed on the tubing 220, the
position of the fitting 300 may be readjusted on the tubing 220, or
a new fitting may be used with the same tubing 220.
[0098] While the preferred embodiment of the invention has been
illustrated and described, it will be appreciated that various
changes can be made therein without departing from the spirit and
scope of the present disclosure. For instance, it should be
appreciated that although the fitting assemblies 200 and 300 are
shown in use with certain collet and ferrule assemblies, the
fitting assemblies 200 and 300 may instead be used with any
suitable collet and ferrule assemblies. Moreover, aspects of the
various fitting assemblies described above may be used in
combination with other fitting assemblies or may instead be used in
isolation.
* * * * *